An argument stands or…
An argument stands or falls on its own merits, not on the appearance of (or any other facts about) the person who is giving it.
You might say that biographical facts about Dworkin (or Flynt or Goldstein) can be useful to understanding why they argue the way the do, or why they focus on what they focus on, or what have you. That’s fine, but that’s not the same thing as evaluating the arguments that they give (which is a matter for logic, not psychoanalysis).
If you try to argue (as obliterati does above) that Dworkin is unattractive and therefore does not need to be taken seriously when she gives moral and political arguments against pornography. This is just an argumentum ad hominem (abusive form). A rather sleazy one, in this case, since it involves nasty personal abuse and participates in well-worn misogynist gambits. Part of the point here is that nobody would think it’s appropriate to treat male scholars this way: if you went around saying things like “Harold Bloom is a fat old pervert. Who cares what he argues about love and sex in early modern literature?” or “Norman Mailer is a ghastly little garden gnome; what does he know about pornography or sex in contemporary literature?” you would (rightly) be regarded as a twit.